Quiros, Carlos F, Andrea Epperson , Hu, J. and Miguel Holle1

Department of Vegetable Crops, University of California, Davis, CA 95616. 1 Genetic Resources, International Potato Center, Lima- Peru.

Econ Bot. (1996) 50:216-223

Experiments based on four accessions of maca (Lepdium meyenii Walp.) disclosed higher developmental rates in plants grown in neutral pH (6.6) soil when compared with those grown in acidic soil (5.3). Photoperiod response studies revealed similar growth rate for plants grown under either long day or short day condition. Plants in the field and growth chambers completed their life cycle in 11 months or less, therefore maca can be considered an annual crop. These results suggest that the range of adaptation of maca is not as narrow as previously believed, and therefore can be successfully produced outside its natural habitat. Chromosome counts and predominance of bivalents in diakinesis and metaphase I disclosed that maca is a disomic octoploid of 2n= 8x=64 chromosomes. Field and growth chamber observations and morphological uniformity of the plants within accessions indicate that maca relies mainly on self-fertilization for its reproduction.

Genetic variability of  Lepidium meyenii and to other Andean Lepidium species (Brassicaceae) assessed by molecular markers.

J.  Toledo1, P. Dehal, F. Jarrin2, F, J. Hu3 , M. Hermann4, I. A. Al-Shehbaz5  and C.F.  Quiros6

Department of Vegetable Crops, U. of California, Davis, CA 95616
1 present address: International Potato Center, POB 1558, Lima 12, Peru
2 present address: International Potato Center Research Station, Quito, Ecuador
3 present address: Lipton, 2029 E. Harding Way, Stockton, CA 95205
4 International Potato Center, POC 1558, Lima 12, Peru
5 Missouri Botanical Garden, POB 299, St Louis, MO 63166-0299
6 corresponding author, (, fax: 530 752 9659

Annals of Botany 82:523-530 (1998)

A phylogenetic survey based on similarity levels was performed for 29 cultivated accessions of maca (Lepidium meyenii Walp.) and 27 accessions of wild species of Lepidium from Ecuador, Peru, and Bolivia, with RAPD markers. Chromosome count for each accession was also performed.  The similarity tree matrix separated in two main branches, the cultivated species and the wild species. The similarity level among cultivated accessions was high (0.952 or higher) indicating low level of polymorphism. Within the wild species, two main secondary branches could be resolved, of which one was subdivided in two tertiary branches. Morphological evaluation of the wild species accessions within each main group identified three wild species: L. bipinnatifidum, consisting mostly tetraploids and a single octoploid accession, L. kalenbornii, consisting only of tetraploid accessions and the third one, L. chichicara, consisting mostly of octoploid and a few tetraploid accessions. Clustering by principal coordinates analysis supported the results obtained by the similarity tree matrix. These results indicate that none of the three wild species is related enough to be considered ancestral to cultivated one, L. meyenii. Three accessions of intermediate positions may be of hybrid origin. None of the wild species was found to be diploid, which suggest that polyploidy has been an important adaptation to high altitude habitats in these species.

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